Bear River Awakening

Flow Needs & Challenges

The non-Yuba portions of the problem-shed include a number of sites that are worthy candidates for conservation action in their own right. Among these are the "salmon occupied" reaches of the lower Bear River as well as Auburn Ravine/Coon Creek (PDF*, 33 KB), Dry Creek/Secret Ravine/Miners Ravine (PDF*, 24 KB), and Dry Creek/Spenceville (PDF*, 19 KB); the middle reach of the Bear River, where Gold-Rush era mercury deposits continue to cause problems; and the upper reaches of the Bear, including a viable native trout fishery (in Bear Valley) that was already the focus of important restoration efforts.

While modest flow improvements would no-doubt be beneficial in the upper reaches of the Bear, our efforts came to focus on its middle and lower reaches, and on the various foothill streams, where diversions are greatest, where flow improvements will depend on the effective re-management of co-mingled inter-basin supplies, and where the regional potential to protect and restore anadramous fish across a diverse array of sites remains high. (In each instance, of course, both flow and non-flow improvements will be needed.) Work to improve flows across a diverse array of sites also underscores the need for a region-wide alliance of restoration advocates.

The middle reach of the Bear River is perhaps the least understood of the sites noted above when it comes to identifying flow-related improvement needs and opportunities. Key challenges for the middle Bear include the following:

While pre-development conditions throughout the watershed supported native trout and other species year-round, pre-development flows (PDF*, 24 KB) during summer and fall months were generally modest across all year types due to the Bear's relatively low-elevation headwaters.

Contemporary conditions in the middle reach of the Bear are such that ecological justifications for improved flows (e.g., protection of native aquatic species) are limited, especially when compared to the lower reach of the Bear or the various foothill streams that continue to support anadramous fish.

Colder water temperatures due to improved summer/fall flows may help to reduce the potential for mercury methylation in this reach and in NCFW Reservoir, but they could also lead to potential conflicts with non-native fisheries (e.g., bass).

The middle reach of the Bear has a predominantly deep canyon profile such that improved flows would likely provide few riparian habitat benefits, however its tributary regions (e.g., Magnolia Creek, Wolf Creek) may serve as refugia for aquatic and wildlife species and the entire middle reach remains an important wildlife migration corridor.

The middle reach contains predominantly private land holdings and provides few opportunities for public access, thus limiting development of an active public constituency for flow-related aesthetic or recreation improvements.

In order to facilitate flow improvements below Combie Dam during minimum release periods, both operational and structural improvements may be needed.

In the lower reach of the Bear, flow improvements may be easier to justify due to the below-dam potential for anadramous fishery restoration; these, in turn, could also serve as a "magnet" for accompanying middle-reach improvements. Even so, a number of problems remain:

Conditions conducive to mercury methylation in NCFW Reservoir, and the resulting accumulation of mercury in fish tissues and other biota, could complicate efforts to improve the downstream fishery (though it is hoped that improved flows would also help to address these problems).

Due to the past accumulation of mining sediments and the presence of overly-constrictive levees, the lower channel has become narrow and incised and will likely require physical remediation as part of any flow-related restoration effort (invasive plant species like Giant arundo will also have to be eradicated).

Like all below-dam environments, downstream gravel recruitment has been limited for many years and would have to be actively supplemented (along with improved flows) to provide suitable habitat conditions for anadramous fish.

NCFW Reservoir is both shallow and warm and may not be able to provide releases or through-flows when needed (i.e., late summer and early fall) at temperatures acceptable to downstream salmon; the result will depend upon the particular reservoir storage and mixing, as well as the volume, timing, source, and temperature of any upstream flow improvements.

In addition to all the above, any effort to improve flows in the Bear River system will depend on the development of agreements and understandings with Nevada Irrigation District (PDF*, 33 KB), Pacific Gas & Electric Company (PDF*, 22 KB), South Sutter Water District (PDF*, 19 KB), Placer County Water Agency (PDF*, 46 KB), and possibly other entities who control and manage water in the system. Flow improvement initiatives can also be advanced through the Federal Energy Regulatory Commission (FERC) license renewal processes for the Drum-Spaulding, Yuba-Bear, and Middle Fork hydropower projects, and/or through other regulatory proceedings, however cooperative strategies have been the focus of this project.

Finally, the contemporary reliance on Yuba (and to a lesser extent American) River imports into the Bear River system leads to concerns among advocates for those resources when considering Bear River and related flow improvements that might constrain future opportunities to "recapture" even a portion of those supplies.